C-6-3

HYGIENIC GROOMING BEHAVIOR INDUCED BY PARASITIC VARROAMITES IN THE JAPANESE HONEY BEE, APIS CERANA JAPONICA RAD.
Hiromi Sasagawa¹, Walter S. Leal², Shigeru Matsuyama³and Christine Y. S. Peng⁴
¹ Intelligence and Synthesis, PRESTO, Japan Science andTechnology Corporation (JST) : c/o National Institute of Sericultural andEntomological Sciences (NISES), Tsukuba, Ibaraki, 305, Japan. ²NISES³Inst.of Applied Biochem., Univ. of Tsukuba, Tsukuba, Ibaraki,305, Japan. ⁴Department of Entomology, University of California,Davis, CA 95616, USA.

The Japanese honeybee (Apis cerana japonica: Acj) and the Europeanhoneybee (Apis mellifera : Am) have been sharing the same habitat in Japansince the introduction of the latter bee species at the turn of the century.Varroa jacobsoni Oud, originally an ectoparasitic mite of A. cerana., hassince infested Am colonies. Heavy infestations of Varroa are commonly foundin the Am colonies, hence the mite has become a major pest of the new hostbee species. In contrast, the colonies of Acj have very few mites. We conductedexperiments to compare the hygienic grooming behavior of Acj and Am inresponse to Varroa parasitism. We report here for the first time the identificationa semiochemical compound, ethyl (Z)-9-octadecenoate (ethyl oleate:EO),from the cuticular extract of Varroa, using GC-MS and GC-FTIR and chemicalderivatization (DMDS), and further established its biological activityin Acj and Am by GC-EAD and behavioral bioassays. We demonstrate that EOis the principle chemical cue used by the Acj worker bees to olfactorilydetect the ectoparasite mites. It is highly potent in eliciting the entirebehavioral sequence of a typical hygienic allo-grooming, which consistsof searching, detecting, and removing the target object with the mandibles.Am worker bees showed no response to mite and mite extract. The biologicalfunction of EO in the bee-mite association is strictly serving as a chemicalcue that triggers hygienic self- and allo-grooming behavior in the Acjagainst their ectoparasitic Varroa mites. This semiochemical role is mostpronounced in the long evolutionary relationship between the mite and Japanesehoney bee.